Mephbashing aside, MM makes a fair enough point. 6-APB is lushy stuff but not sure it's necessarily a Powder of Filth as such. Never tried it in such a situation though so maybe - 2C-B sex is probably the bestest sex ever
I'd like to give more drugs a try in that department but the fact is that most of my girlfriends have been non-drug-users (alcohol and cannabis aside) so they've often been less keen on the idea of getting filthy with a guy who's talking pretentious crap about 'syncretism' and 'ontological remapping' that they (and probably he) neither know nor care to know about. Or a sweaty / gurny / noddy mess.
That said, in a one-sided sense I've enjoyed MDMA sex (though it was often an effort) MDA sex (which wasn't), heroin sex (it doesn't always kill your libido) speed sex (had to spend time alone in the toilet making sure I wan't about to present her with a dick shrunken to the size of a shrivelled Wotsit) and even low-dose acid sex with a curious lesbian I thought just wanted a drinking buddy and a place to kip. I'd like to explore 2C-B sex with somebody other than the person I did experience it with, for various reasons.
On the rare occasions I've had sex with a partner sharing the same drug experience, it's been mindblowing in very different ways. Mushroom sex can get to the point where the physical, penetrative act comes secondary to feeling of melding with another sentient being.
Cocaine sex is just excessive horniness, delayed ejaculation (not always ideal), vastly-improved stamina, tendency to get violent to just the right degree... one of the only good things about it. Scratching, biting, unselfconscious degrading behaviour and the type of talk that'd normally make you laugh your guts up with its cheesiness.
I now have my libido somewhat restrained by my opioid intake, but things still function should they be called into action.